If your eyes glaze over , they become dull and lose all expression, usually because you are bored or are thinking about something else.
...movie actors whose eyes glaze over as soon as the subject wavers from themselves.
PHRASAL VERB : V P
GLAZE OVER
Meaning of GLAZE OVER in English
Collins COBUILD Advanced Learner's English Dictionary. Английский словарь Коллинз COBUILD для изучающих язык на продвинутом уровне. 2006